Fruit appearance improvement by using filter-attached paper bags in 'Niitaka' pears.

Fruits on ‘Niitaka’ pear trees (Pyrus pyrifolia) were managed with bagging for the purpose of appearance improvement at the experimental field in National Institute of Horticultural and Herbal Science, Suwon, Korea from 2003 to 2005. The paper bag consisted of outer and inner layers of yellow and yellow papers or black and blue papers with or without filter attachment. The application of double layer paper bag in pear fruit management brought about wide numeric distribution in certain measurements of fruit characteristics as 631.2 to 650.5 g in fruit weight and 204 to 231 N in flesh firmness, but failed to show statistical significance. However, fruit skin coloring was significantly improved by the application of double layer paper bag. The Hunter values were slightly increased by the application of normal type paper bag recording up to 49.9 in ‘L’ and 22.4 in ‘b’ and demonstrated more or less large increase by the application of filter-attached paper bag recording 54.4 in ‘L’ and 22.9 in ‘b’. Fruits with normal type paper bag showed the incidence frequencies of fruit skin damage as 14.2% by air pollutants and 8.3% by insects (Pseudococcus comstocki). These frequencies were significantly decreased by the application of filter-attached paper bag, reducing to approximate 2% in both observations. Fruits with normal type paper bag showed severe occurrence of skin russet on fruit stalk cavity by the abundant amount of inflowing air pollutants on epidermis. The application of filter-attached paper bag noticeably decreased the skin russet occurrence and the inflow of air pollutants.